Hydrocarbon conversion process



Jan. 2, 1934.

w. B. PLUMMER HYDROCARBON CONVERSION PROCESS Filed Aug. 25, 1932 m kiouoY I INVENTOR william lwzzmer BY-gmlgii ATTORNEY I Y I Patented Jan. '2,1934 PATENTI- OFFICE 1,941,577 I HYDROCARBON CONVERSION PROCESS WilliamB. Plummer, Chicago, 111., assignor to Standard Oil Company, Chicago,Ill., a corporation of Indiana Application August 25, 1932. Serial No.630,336

4 Claims. (01. 196-10) My invention relates to an improved method forthe polymerization of gaseous olefins to form higher boil ng liquidproducts.

It is well known that rich olefinic gases, in other 5 words, gasescontaining more than 50% of gaseous olefins, can be polymerized atpressures of 500-3000 pounds per square inch and at temperatures of 700to 950 or 1000 F. It is also known that lean olefinic gases containingless 0 than 50% of gaseous olefins can be polymerized under these samepressures at slightly higher temperatures of about 950-1250 F. Varioussystems for the polymerization of rich olefinic gases have beenproposed, and other systems have been proposed for the polymerization oflean olefinic gases. In both cases it has generally been proposed torecycle all or a part of the unconverted gases which are separated fromthe liquid products.

I have discovered that in operating systems for the polymerization ofrich olefinic gases, the olefins present in the original gas are largelyconverted to liquid products, and since relatively little or no crackingtakes place under these conditions, it is not ordinarily possible toseparate from liquid products a recycled gas having a concentration ofolefins as high as the original rich gas and hence that direct recyclingresults in a,

diluted total feed. On the other hand, I have found that in systems forthe polymerization of lean olefinic gases, due to the appreciable amountof cracking (of parafiinic gases present) that takes placesimultaneously with polymerization in this temperature range, it ispossible to separate from the products a recycled gas having an olefinconcentration appreciably higher than the original lean olefin gas.Recycling of such gas to a heater operating under conditions favorablefor lean gas polymerization is undesirable, since these conditions areunduly severe (as re 'gards temperature) for the treatment of richerolefin gases.

I have further discovered that by operating a lean gas polymerizationsystem and a rich gas polymerization system in conjunction with eachother in the sense that recycled gas separated from liquid products ineach system is returned to the heating and reaction section of the othermate yield of products andin the capacity and specification representsa; diagrammatic elevasystem, very considerable increases in theultitional view of suitable apparatus for carrying out my improvedprocess;

The basic principle of my invention is clearly set forth by theforegoing brief description. The actual operation of my improved systemmay be described as follows:

Referring to the drawing, lean olefinic gas may be supplied thru line 10and compressed by pump 11 to 500-3000 pounds per square inch, whereafterit is heated by heater 12 and caused to react at temeratures of 950-1250F. Heater 12 may be followed by soaking chamber 13, or if the coils ofheater 12 are suificient in volume so that the reactions are essentiallycomplete at the exit thereof, valves 14 and 15 may be closed wherebysoaking'chamber 13 is cut out of the system and products leaving theheater 12 pass thru valve 16 in by-pass 1'2. Ineither case totalproducts pass thru andare cooled in cooler 18, then passing thru offtake19 and valve 20 to separator 21, which ordinarily operates at fullreaction pressure and from which fixed gases may be withdrawn andeliminated from the system thru vent 22. Liquid products and dissolvedgases are drawn off thru 23, the pressure reduced at valve 24 wherebyadditional quantities of gas are separated iii-separator 25 which isprovided with vent 26 and ofitake 27. Liquid products may be drawn offthru 28 or, if desired, a third separator may be provided, in which caseseparator 25 is operated at an intermediate pressure and liquid productsand remaining dissolved gases from 25 passthru line 29 and valve 30 intoseparator 31, which is operated at a further reduced pressure and isprovided with vent 32 and gas offtake 33, final liquid products beingwithdrawn 3 thru 34. Gas ofitakes 27 and 33 communicate with line.35 andpump 36 whereby rich olefinic gases separated in 25 and/or 31 may beintroduced into the inlet of my second polymerization system.

The second polymerization system may be, and is shown as being,identical as regards arrangement with the first system and elements ofthe second system have the same function and relation to each other asthe correspondingly num-. bered elements of the first system. The secondsystem need not therefore be described in detail. The heater 12' and thesoaking drum 13 (if used) operate in the same pressure range of 500-3000pounds per square inch as the first system, but operate in a lowertemperature range of 700-950 F.

In this system gas from separators 25' and/or 31 is of lower olefincontent than the rich gas supplied thru 10', and the lean gas fromofftakes 27 and/or 33 is therefore passed thru line 35' and pumped bypump 36' to the inlet lo of the heater 12 of the first polymerizationsystem.

Under some conditions if I make use of a plu= rality of separators 21,25, 31, etc. and 21, 25', 31, etc. I may obtain from one of theseseparators a gas of suitable olefin content to be recycled to the samesystem, in other Words, a gas havessentially the same olefin content asthe gas feed to the system. I two systerns E there fore provide recyclelines 3'? and 37 returning in each case to the inlet of the same system.Separators 25 and 25' respectively, communicate with lines 37 and 37"thru offitalre '38 and valve 39 and ofitake 38' and valve 39'respectively. Similarly separators 31 and 31' communicate with 37 and37" respectively thru oiltalre l0 and vs ve 1, and oiitake so and valve41' espective." this means 1 may operate my various se, a so as toobtain separate gases of both high and low olefin content retreat thsegases respectively under the pol inerization con ""ions most suitedfor their particular olefin content. I;

all

my first system, i. e. that operating on lean I may also recycle part orthe gas separated l sigh pressure separator 21, which is ther icreconnected with recycle line 37 by line 42 and valve 43.

will be evident m whole system may be op ated by supplying loo richolefin gas and olefin gas from external sources to app priate inlets itand of the system or that l feed my system 'with either rich olefin orlean oleiln gas alone, which case of the system operates only onrecycletl from the other half of the system wi hout adr esponding freshgas. w

of coils receives The operating cored ions of -nressrue senarators or21' are si'hject to the limitation that frequently it is pre not tooperate said separators at pressu s alcove lbs. per square inch since atthe t l perattres attainahle with ordinary cooling separation of phasesis iently not at m they to he understood having the meaning as defined.By rich olefin gas .i. a mixture containing over 59% gaseous oleflns voltime. lean olefin gas 1 mean a gas contaim ing less than 5c% of gaseousolenns Toy volume.

merization at high temperature sure, separating a rich olefinic gaspi'cductsof said high temperat e s eturning said rich oleiinic gas to tfirst named low temperature polylnen tern.

2. the polymerization of ole-nine liuricl products, the steps ofsubjecting lee ole finic gas to polymerization at high ten i erature andhigh pressure, separating rich olefinio gas from reaction products ofsaid high temperature l ystein, subjecting said rich olefinic gas tonoly lleilzation at low temperature and hi h pressure, separating a leanoleflnio gas from reaction. products of said low temperature system, andtiuning said lean olefinic gas to the inlet of the first named hightemperature polymerization sys liquid products, the steps of subjectingrich ole fiiiic to polymerization at low temperature high pressure,subjecting lean olefinic gas to polymerization at high temperature andhigh pressure, separating a lean olefinic gas ircrnv liquid products ofthe low temperature system and a rich olei'hiic gas from reactionproducts of the nerature system, and admixing said sep arated l anolefinic gas and said separated rich ov linic with the correspondingstreams of olefiiiic gas and rich olerinic gas supplied to the hightemperature and low temperature systems respectively.

4;. in the polymerization of olefinic gases to finic gas topolymerization at low temperature and high pressure, subjecting leanoleilnic gas 1 to polymerization at high temperature and high pressure,separating gases from products in a plurality of stages in each system,withdrawing a lean olefinic gas from at least one separating stage ineach system, withdrawing a rich olei finic gas from at least oneseparating stage in each system, uniting said separated rich oleflnicgas from both systems and subjecting said coinhined rich olei'lnic gasto polymerization at low temperature and high pressure, uniting said senarated lean oleiinic gas from both systems, and subjecting said leanoleilnic gas to polymerization at hi h temperature and high pressure.

*JVlLliiAil/I l3. Z LUEIZMER.

